Paramedics were called to Camacho's girlfriend's home in West Covina Monday. They performed CPR but could not save his life. Camacho, 41, was declared dead at Citrus Valley Medical Center-Queen of the Valley Campus.
Dozens of his friends, students and loved ones gathered to honor his memory at UFC Gym in Rosemead following news of his death.
"He would always give me tips, advice on what to do during a match," said Hector Ruiz, 16. "Or even in just regular life -- how to talk to people, how to greet people, mannerism ... he was a really good guy."
Camacho's girlfriend, Maggie Arechiga, says he complained of chest and arm pains Sunday night while at her home. She believed he was having a heart attack and said she'd take him to the hospital.
"He didn't want to, and his last words to me were 'I love you' and he put the blanket over himself," said Arechiga.
Arechiga says Camacho was used to pain and maybe thought he could win this fight. Despite her grief, she says she wanted to be strong at Monday's candlelight vigil.
"I just got some strength out of nowhere, maybe it was Joe," said Arechiga. "He put it in me and let me go out there and put a smile on everyone else's faces like I know he would have."
Camacho had recently opened his own Brazilian Jiu-Jitsu Academy in downtown Los Angeles.
"He was incredibly patient and he believed in you when you didn't believe in yourself," said Sergio Quintero, who trained with Camacho at the UFC Gym.
Camacho's teaching style earned him a tremendous amount of respect and a loyal following of fighters of all levels.
"He was a good friend. I'm sad to see him go," said Quintero.
It remains unknown if Sunday's competition played a role in his death. An autopsy is scheduled to determine Camacho's exact cause of death.